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Summary of Foam Coefficient of Friction

Biomch-L,

Following my original question is a summary of replies. Thank you to those
who replied. However, there seems to be little information on contact
between foam/compressible/rubber like materials and human skin. The
material properties for EVA displayed on the web (www.matweb.com) seem to
concentrate on moulded/extruded resin grade materials.There are quite a few
listed polyurethane, polycarbonate and polypropylene foams but most state
that they can custom formulate the foam and vary the physical properties
(coefficient of friction, abrasion resistance, hardness and density) to
suit various applications and therefore do not provide a value. I thought
there may be enough sports around (including water sports) that require
padding as well as surface testing that may have included this type of
investigation.

Regards,
Justin

Original Question:
>Biomch-L Colleagues,
>I have been looking at Ethylene Vinyl Acetate (EVA) foams used as a soft
>padding on certain water sport equipment.There are also certain types of
>Polyethylene (PE) that are used. I was looking to find an estimate of the
>coefficient of friction between these soft, 'rubberised' foams and the
>human foot in both wet and dry conditions. I have searched on the net with
>little success and most literature that I have found on these type of foams
>lies in the footwear field and thus the coefficient of friction studied is
>the footwear to surface interface rather than the foot to foam interface. I
>was wondering whether anyone knew of any research that might help me.
>Your help would be greatly appreciated and a summary will be posted.
>
>Thanks,
>Justin

RESPONSE 1:
Justin,

www.matweb.com has everything you'll every need to know about material
properties
I did a search for Ethylene Vinyl Acetate and got 175 types.
Ethylene Vinyl Acetate Copolymer (EVA), Extrusion/Coating Grade
has a coefficient of friction of 0.63

hope that helps
Josh Good

RESPONSE 2:
see Buck and Bär "Investigations on the biomechanical significance of
dermatoglyphic ridges"
in "Hands of Primates" ed. by Preuschoft and Chivers, Springer Vienna ISBN
3-211-82385-9

and

Dear Mr. Ludcke,
this is a short excerption of Buck and Bär (1993), mentioned before.
Dermatoglyphic ridges play an (underestimated) role in static friction more
than in slide friction in all materials tested (pine wood, glass, marble,
and grey polyvinylechloride). This means that the frictional resistance
perpendicular to the dermatoglyphic ridges is on average about 20% higher
than in directions with them in static friction. Results also differ for
different fingers. I think this might be important for the ergonomic and
safe design of handles and surfaces and useful for your thesis. If you are
interested in the source and facing problems you´re invited to contact me.